Auxiliary diagnostic apparatus comprise magnetic resonance (MR) systems, ultrasonic systems, computed tomography (CT) systems, positron emission tomography (PET) systems, nuclear medicine and other types of imaging systems.
For example, during CT imaging of a patient by a CT system, X-rays are used for imaging features of inner structures and regions of interest (ROI) of the patient body. The imaging is performed by a CT scanner. In operation, a photograph object is scanned for collection of raw data, and then an image is reconstructed based on the raw data.
An object having high X-ray absorption characteristics such as metal materials and so on can cause artifacts in the reconstructed CT image and thus influence the results of diagnosis. These artifacts can be reduced using existing Metal Artifact Reduction (MAR) techniques. The algorithm of MAR is very complex and its results vary with the properties of metal (e.g., the size, material and shape of the metal).
Clinically, in the case of an artificial knee joint, because it comprises a large volume of metal part and the metal part occupying a large proportion of the cross section of the knee, despite the use of a MAR technique, the metal artifacts of the knee are not significantly reduced as compared with those smaller bone implants that occupy a small proportion of the cross section. This affects the doctor's diagnosis.
Clinically, in the case of an artificial metal tibia, it occupies a small proportion of the cross section of the knee. The use of a MAR technique can cause other problems such as the occurrence of halo around the metal in the image reconstructed using the MAR technique and loss of some image of the metal part. This also affects the doctor's diagnosis.